Not currently, and it would only be safe if you had never given out any of the addresses you delete. Otherwise, someone could send some to that address and those coins would be out of circulation forever, or until SHA256 is broken, whichever comes first.

Best way (IMO) would be to create a new wallet, send your balance there, and archive your old one.

It would be useful if the addresses could at least be ordered by name instead of only by address. How do you guys manage to find the addresses you're actually looking for? It's starting to become a real challenge to me .

Do you use the client without the gui, like with some custom build interface, maybe directly with bitcoind? Because the default client is using the addresses to order the address book entries, not the labels. If I could order them by the label I would also find my stuff.